Two-compartment ball-mill



I. R. BALL.

TWO COMPARTMENT BALL MILL.

APPLICATION FILED APR. 24, I9I9.

Patented Maf. 30, 1920.

lmflwuun 3mm/woz JZ BQ ZZ 1. R. BALL. TWO COMPARTIVIENT BALL MILL.

' APPLICATION FILED APR. 24, I9I9.

- Patented Mar. 30, 1920.

2 SHEETS-SHEET 2..

51m/newton' JOHN B. BALL, OF DURANGO, COLORADO.

Two-comrAnTniEnT BALL-MILL.

To all 'whom it may concern:

Be it known that I, JOHN RQBALL, a

` citizen of the United States, residingat Durango,

State of Colorado, have invented certain new and useful Improvements in Two-Compartment Ball-Mills; and I dodeclare the following to be a full', clear, and exact descrlption of the invention, such'as will enable others skilled in the art to which 1t apf pertains to make and use the same.

My invention relates to that class of ore grinding mills commonly Aknown as ball mills. Heretofore, it has been common practice to provide a rotating cylinder divided by perforate partitions 1nto a number of grinding compartments, the ore being ground by balls to a predetermined degree of fineness in, each compartment and then discharged into 4 the next,luntil it finally reaches the outlet.

The fact that ballsare used in the final grinding compartment as weil as in the others, and the particles of o may freely fall 'through the s aces between. the balls without being cruslied to any appreciable extent by the latter, necessitates slow operation, andthe principal object of -my invention is, therefore, to provide sliding, gravityoperated mullers in the final grinding com partment to overcome this difliculty, and since these mullers produce a s lashing action the screens instead o f being vforced therethrough by pressure, with the result that the life of the screen" is greatly increased. In

this connection, astill further object is to terminate the discharge screen I in Vspaced, relation with the wall of the rotating cylinder so that the end` portion of the end wall which carries said screen forms a rim' around the latter, the mullers being of less vertical thickness than the radial width. of such rim, -so that they do not wear upon the screen.

With the foregoing objects in view, the

invention resides 1n the novel constructionand association of parts hereinafter fully described and claimed, the descriptive matter being supplemented by the accompanying drawings which form a part of this application.

Figure invention. i

Fig. 2 1s a vertlcal transverse section on Specication of Letters Patent.

in the county of La Plata andv the pulverized ore 1s was ed through 1 is a vertical longitudinal section' of a mill constructed in accordance with my.

Paten-ted Mar. 30, 1920.

Application med A1ir1124 ,191a serial No. 292,342.

the plane indicated by the line- 2-l-2 of Fig'. 1.

Fig. 3 is a detail horizontal section on the" plane of line 3 3 of Fig. 2.

.Inthedrawings above brieiy described, i

vthe numeral 1 designates a horizontal grind-l ing cylinder rotatablyl mounted yon trunnions 2 and 3, both of which are of tubular formation and are provided with helical internal conveyers 4. The trunnion 2 is provided with a spiral collecting head 5A and 'ordinarily' ore is fed to the machine f i through said head and trunnion, but if such ore is sufficiently` fine not to require re.' liminary grinding, it may be well to vfecd yto the final grinding chamber by way of l Preferably located centhe v trunnion 3.

trally between the two end walls 6 and -7 of the cylinder 41 is a flat transverse partition 8 of circular formation with its peripheral.-

edge suitably secured-to the peripheral wall 9 of the cylinder, said partition dividingthe cylinder into a preliminary grinding chamber 1 0 and a final 'grinding chamber' 1l. The trunnion 2 discharges into the chamber 10 andl by means 'of '-a single' central' opening 12 in thepartition 8, the two compartments 10 and 11v are placed in commu'- nication. The end Wall 7. rwhich forms. one

of the sidev vwalls of the final grinding',

chamber 11 is lprovided with a discharge screen 13 preferably formed of a number' of sections suitably secured in place. The particular form of screen'does not affect the present invention, is protected by a prior appllcatlon, and need not, therefore, be described in detail. however, that the screen terminates in spaced relation with the wallv9 so that the peripheral portion of the wall 7 forms a It. may be set forth,

rim 14 around said screen, as is seen most clearly in Fig. 2, this rim serving toprevent the mullers 15 in the final grinding cham-- ber y11 from wearing against the screen,`

since said mullers are of less vertical thick'- ness than the radial width of the rim.

Crushing balls 16 are rovided in the preliminary grindingvcham er 10 for initially grinding the ore as it is discharged into such compartment from the trunnion 2, and

in order to prevent these balls and the mullers 15 from wearing the permanent parts of the mill, thewall 9 is provided with ay ribbed lining 17 and the partition 8 and the ends of the cylinder are lined at 18. The particular form of lining does not affect the present invention and is protected by a prior application; it, of course, bein understood that any adequate form of limng may well be used, but it spreferable that ribs 19 be provided thereon forv coperation with the balls and mullers.

The mullers 15 are preferably in the form of substantially fiat rectangular blocks with their edges rounded at 20 for easy passage over the ribs 19, one edge of each muller being provided with two or more projecting lugsV 21. These lugs space the several mullers apart to provide gaps 22 through which the ore may pass. As shown, 'the mullers are substantially equal in width to the compartment 11 so that they cannot be displaced therein, but must slide, as intended, in a circumferential direction.

In operation, the ore-laden slime is fed to the preliminary grinding chamber 10 by means of the hollow trunnion 2 or any other inlet which. may be provided for this purpose, and the ore is initially ground by the balls 16, the ground ore rising toward the surface of the slime and passing freely through the single dischargeopening 12 into" the final grinding compartment 1.1. In this compartment, the mullers 15. operate upon the ore and reduce it to the required degree of fineness, and since these mullers will vmove bodily with the cylinder 1 until they slide down the cylinder wall by gravity, they produce a splashingaction in -the slime which washes the ground ore4 through the screen 13 instead of forcing it therethrough by pressure, as occurs when using balls in the final grinding compartment wear upon the screen is thus prevented, which would` otherwise take place not only by forcing the ore therethrough, but by the action of the balls against said screen. Since the mullers 15 contact against the rim, 14: and not againstl the screen, there isno danger of wearing the latter and consequently lits life is greatly lengthened. In addition to the above mentioned advantages for the mullers 15, they grind the ore more effectivelythan the ordinary balls commonly used 1n the final grinding chamber.

From the foregoing taken in connection with the accompanying drawings, it will be seen that' although the improved mill is of comparatively simple and inexpensive na. ture, it will be highly eilicient and desirable and ywill overcome dliiiculties heretofore eX- perienced, being much more rapid in operation and less subject to over feeding, due to the provision of the central opening 12 in the partition 8 which allows the free .discharge of the ground material from the preliminary into the final grinding chamber, and the mullers 15.

Since probablyl the best results are obtained from thedetails disclosed, theymay well be followed, but within the scope `of the invention as claimed minor changes may well be made and screens of any required form or mesh may lbe used. Also, it will be understood that the machine may be used not only for grinding ores, but for cement and numerous other materials, and it has been found that grinding may be done to an ing capable of independent movement, andy means carried by one muller to abut the next muller and form an intervening space when the two come together.v A

2. In a mill of the class described, a rotary cylinder mounted on a horizonal axis and provided with ore inlet and discharge means, and a pair of freely sliding mullers in said cylinder operating against thel peripheral wall thereof and capable of independent movement, one of saidmullers having projecting lugs rigidly carried thereby to abut the other muller and form an intervening space when the two come together.4

In testimony whereof I have hereunto set my hand.

i JOHN n. BALL.k 

